The present invention relates to optical apparatuses and, more particularly, to optical apparatuses using a variable-optical-characteristic optical element.
Conventionally, lenses, mirrors and so forth are used in optical apparatuses. These optical elements have invariable optical characteristics. That is, the focal length thereof, for example, is not variable. Therefore, in order to effect focusing or zooming, for example, it is necessary to move lenses, etc. This causes the whole optical apparatus to become unfavorably heavy in weight and large in size.
Conventional digital cameras have an arrangement in which an image display device, an imaging lens and a solid-state image pickup device are fixedly accommodated in a single box. Therefore, the conventional digital cameras have the disadvantage that they cannot be made compact and hence become unfavorably heavy. Further, because the definition (pixel density) of solid-state image pickup devices is becoming increasingly higher, the overall functions of digital cameras rapidly become obsolete. Meanwhile, there is a demand for a compact, lightweight and low-power consumption image pickup system for use in portable telephones, portable information terminals, capsule and other endoscopes, etc. In this regard, an image pickup system using the conventional method in which an optical system consisting of lenses and other optical elements is driven by a motor is large in size and heavy in weight and suffers unfavorably high power consumption.